Biomedical subjects

M Zdanowicz

Publications and source records attributed to M Zdanowicz.

10 recordsLinked to original sources

PubMed2004

Bacterial populations on teat ends of dairy cows housed in free stalls and bedded with either sand or sawdust.

The main objectives of the experiment were: 1) to compare bacterial populations of mastitis-causing organisms on the teats of lactating dairy cattle housed on sand and sawdust bedding and, 2) to examine the relationship between bacterial counts present in the 2 bedding types with those on teat ends. Sixteen lactating Holstein cows were housed on either sand or sawdust-bedded free stalls using a crossover design with 3 wk per bedding type. Bedding samples were collected on d 0 (prior to animals lying on the bedding), 1, 2, and 6. Teat ends were sampled prior to the morning milking on d 1, 2, and 6. All samples were analyzed to determine coliform, Klebsiella spp., and Streptococcus spp. populations. There were 2 times more coliforms and 6 times more Klebsiella bacteria on teat ends of cows housed on sawdust compared with those housed on sand. In contrast, there were 10 times more Streptococcus spp. bacteria on teat ends of cows when housed on sand compared with sawdust. In both sawdust and sand bedding, coliforms, Klebsiella and Streptococcus counts increased over each experimental week, although patterns varied with bedding and bacteria type. Bacterial counts on teat ends were correlated with bacterial counts in sawdust (r = 0.47, 0.69, and 0.60 for coliforms, Klebsiella spp., and streptococci, respectively) and in sand (r = 0.35 for coliforms and r = 0.40 for Klebsiella spp.). In conclusion, coliforms and Klebsiella spp. on teat ends were more numerous when cows were housed on sawdust bedding, but Streptococcus spp. were more numerous on teat ends of cows housed on sand.

Animals↗

PubMed2004

Role of antioxidants in the protection against oxidative stress in cattle--trace elements and enzymatic mechanisms (Part 3).

The most important enzymatic mechanisms which protect an organism against oxidative stress are superoxide dismutase (SOD), peroxidase (Px), e.g. glutathione peroxidase (GSH-Px) and ascorbate peroxidase, catalase and glutathione reductase. Their activity depends on many trace elements. Enzymatic mechanisms, functioning under physiological conditions, prevent the spread of free radical reactions. New and reoccurring metabolic and infectious diseases of cattle emerge when there is a disproportion in the balance between reactive oxygen species and antioxidative enzymatic barrier.

Animal Feed↗

PubMed2003

Role of the antioxidants in the protection against oxidative stress in cattle--nonenzymatic mechanisms (Part 2).

Antioxidative status consists of two mechanisms: nonenzymatic and enzymatic mechanisms. Nonenzymatic mechanisms are composed of antioxidants, scavengers of free radicals, transition metal ions, sequester transition metal ions, albumins, ceruloplasmin, and metallothioneins. On the other hand, enzymatic mechanisms are composed of superoxide dismutase (SOD), peroxidase, catalase and reductase. In cattle, characteristics of these mechanisms depend on the nutritional status of anti-oxidant minerals, especially copper, zinc, iron, selenium, silicon, and manganese. The nutritional status of the cattle in different regions of the world and in Poland is often characterised by the lack of these minerals; therefore, there is a great potential for changes in the activity of defence mechanisms against free radicals.

Animals↗

PubMed2002

Role of transition metals ion and reactive oxygen species in biological oxidation in cattle (part 1).

Technological advances in last decades of XX centuries were well utilised in the studies of biological oxidation processes. Biological oxidation can lead to the oxidative stress and subsequently to the cell damage of animal organisms leading to many diseases. Free radical processes taking place in cattle under pathological conditions. Metal ions are often responsible for the damage of biological systems. Fenton and the Fenton like reactions can play the central role in the oxidative stress. Transition metal ions and their complexes catalyse Fenton and the Fenton like reactions.

Animals↗

PubMed2001

Outpatient commitment: what, why, and for whom.

The authors describe studies showing the effectiveness of involuntary outpatient commitment in improving treatment compliance, reducing hospital readmission, and reducing episodes of violence among persons with severe psychiatric illnesses. They point out that because of its role in enhancing compliance with treatment, outpatient commitment can be regarded as a form of assisted treatment, such as assertive case management, representative payeeship, and mental health courts. The authors argue that such assisted treatment is necessary for persons with severe psychiatric illnesses who are noncompliant with their medication regimens because many lack awareness of their illnesses because of biologically based cognitive deficits. They recommend outpatient commitment for any individual with a severe psychiatric disorder who has impaired awareness of his or her illness and is at risk of becoming homeless, incarcerated, or violent or of committing suicide, and they provide case examples. The authors conclude by addressing eight of the most common objections to outpatient commitment by mental health professionals and civil liberties groups that oppose outpatient commitment.

Civil Rights↗

PubMed2001

Analysis of Cx43alpha1 promoter function in the developing zebrafish embryo.

The Cx43alpha1 gap junctions play an important role in cardiovascular development. Studies using transgenic mouse models have indicated that this involves an essential role for Cx43alpha1 in modulating neural crest cell motility. We previously showed that a 6.8 kb mouse genomic sequence containing the promoter and upstream regulatory sequences of the Cx43alpha1 gene can drive lacZ reporter gene expression in all neural crest cell lineages in the mouse embryo. To obtain further insights into the sequence motifs and regulatory pathways involved in targeting Cx43alpha1 gene expression in neural crest cells, we assayed the activity of the mouse Cx43alpha1 promoter in evolutionarily distantly related zebrafish embryos. For these studies, the 6.8kb Cx43alpha1 genomic sequence and various deletion derivatives were used to generate GFP or lacZ expression vectors. The transcriptional activities of these constructs were analyzed in vivo after microinjection into one- or two- cell stage zebrafish embryos. These studies indicated that the mouse Cx43alpha1 promoter can drive lacZ expression in neural crest cells in the zebrafish embryos. Analysis by whole mount in situ hybridization showed that the endogenous zebrafish Cx43alpha1 gene is expressed maternally and zygotically, and expression is observed in regions where neural crest cells are found. To further elucidate the developmental regulation of Cx43alpha1 gene expression, we screened a zebrafish BAC library and identified a clone containing the entire zebrafish Cx43alpha1 gene and flanking upstream and downstream sequences. The upstrean Cx43alpha1 promoter sequences from zebrafish, mouse, and human were analyzed for evolutionarily conserved DNA motifs. Overall these studies suggest that the sequence motifs and transcriptional regulation involved in the targeting Cx43alpha1 expression to neural crest cells are evolutionarily conserved in zebrafish and mouse embryos.

Animals↗

PubMed1999

Use of a repetitive mouse B2 element to identify transplanted mouse cells in mouse-chick chimeras.

Monitoring the migrations of cells during embryonic development requires a system in which cells can be identified in situ during locomotion. One promising system involves the generation of chimeras by transplanting mouse cells into chick embryos in ovo to exploit the wealth of mouse genetic variants. The success of this technique relies on the ability to detect individual mouse cells in a chick environment with high specificity. The murine B2 family of short interspersed elements is present in the mouse genome at copy numbers in excess of 10(5), whereas this sequence is absent in the chick genome based on hybridization techniques. This differential of five orders of magnitude produces signals in mouse cells that are easily identified, even in an environment that is predominantly chick. Thus, the B2 repeat probe is highly effective for the purpose of identifying mouse cells in mouse-chick chimeras.

Animals↗

PubMed1999

A novel role for cardiac neural crest in heart development.

Ablation of premigratory cardiac neural crest results in defective development of the cardiac outflow tract. The purpose of the present study was to correlate the earliest functional and morphological changes in heart development after cardiac neural crest ablation. Within 24 hours after neural crest ablation, the external morphology of the hearts showed straight outflow limbs, tighter heart loops, and variable dilations. Incorporation of bromodeoxyuridine in myocytes, an indication of proliferation, was doubled after cardiac neural crest ablation. The myocardial calcium transients, which are a measure of excitation-contraction coupling, were depressed by 50% in both the inflow and outflow portions of the looped heart tube. The myocardial transients could be rescued by replacing the cardiac neural crest. The cardiac jelly produced by the myocardium was distributed in an uneven, rather than uniform, pattern. An extreme variability in external morphology could be attributed to the uneven distribution of cardiac jelly. In the absence of cardiac neural crest, the myocardium was characterized by somewhat disorganized myofibrils that may be a result of abnormally elevated proliferation. In contrast, endocardial development appeared normal, as evidenced by normal expression of fibrillin-2 protein (JB3 antigen) and normal formation of cushion mesenchyme and trabeculae. The signs of abnormal myocardial development coincident with normal endocardium suggest that the presence of cardiac neural crest cells is necessary for normal differentiation and function of the myocardium during early heart development. These results indicate a novel role for neural crest cells in myocardial maturation.

Animals↗

PubMed1995

Short- and long-term effect of oral salbutamol on growth hormone secretion in prepubertal asthmatic children.

Salbutamol, a beta 2-adrenergic agonist, is being extensively used in Venezuela as a brochodilator in the treatment of asthma in children. Previous reports have shown oral salbutamol either to inhibit or not to affect growth hormone (GH) secretion. We evaluated the effect of oral salbutamol (0.1 mg/kg every 6 hours for 3 months) on GH secretion in eight prepubertal short children with mild asthma. Levels of GH during sleep (samples taken every 30 minutes from 9 PM to 6 AM) and after GH-releasing hormone ([GHRH] 1 microgram/kg intravenously [IV]) were measured before, at 24 hours, and at 3 months of salbutamol treatment. Overnight integrated concentrations of GH and peak GH levels following GHRH diminished significantly after 24 hours of salbutamol therapy (from 4.5 +/- 1.3 to 3.4 +/- 0.8 micrograms/L and from 46.6 +/- 47.3 to 16.2 +/- 7.9 micrograms/L, respectively, P < .05). However, GH levels after 3 months of salbutamol were not different from basal levels (4.5 +/- 1.3 v 5.1 +/- 5.1 +/- 2.9 micrograms/L during the overnight studies and 46.6 +/- 47.3 v 37.8 +/- 30.4 micrograms/L after GHRH). Our data suggest an inhibition of both spontaneous and stimulated GH secretion following short-term oral salbutamol ingestion, but this suppressive effect is not maintained with its long-term use.

Administration, Oral↗

PubMed1989

Morphologic and functional alterations in absorptive epithelial cells during L-tryptophan induced inhibition of net sodium and fluid absorption in the rat ileum.

L-Tryptophan (L-Trp) has been reported to suppress jejunal fluid and electrolyte transport in vitro, at a 20 mM concentration, whereas other amino acids enhance that absorption at the same concentration. The effect of L-Trp, glycine (Gly) and L-phenylalanine (L-Phe) on in vivo ileal and jejunal fluid and sodium transport, and their morphologic correlates, were investigated in the rat. In the ileum, morphology as well as fluid and sodium transport were more readily altered by L-Trp than in the jejunum. The ileal effects were rapid; morphologic and transport changes were seen within 2.5 minutes. The changes were stereospecific; they occurred only with the levo, but not with the dextro isomer of Trp. There was a concentration dependence; 20 mM levels of L-Trp were required, whereas lower concentrations of the amino acid often stimulated net absorption. Morphologic alterations produced by L-Trp were restricted to absorptive epithelial cells, whereas goblet cells appeared unaffected. Morphologically, L-Trp treatment led to the formation of clear basal vacuoles in ileal absorptive epithelial cells at 2.5 minutes, and extensive vacuolization and loss of the lumenal permeability barrier to macromolecules at 30 minutes. Since L-Trp can be hydroxylated in the small intestine, we assessed the effects of L-5 = OH tryptophan and 5-hydroxytryptamine on small intestinal transport and morphology in this experimental system. L-5-OH tryptophan inhibited fluid transport and produced some epithelial cell vacuolization. However, 5-hydroxytryptamine, which most severely decreased transport, had none of the morphologic effects of L-Trp. We hypothesize that L-Trp may inhibit transport as a result of its intracellular accumulation in absorptive epithelial cells.

Animals↗